U.S. Pat. No. 6,021,873 describes a load measurement device located at the dead end hitch. The tension member terminations are mounted to a bracket, which is in turn mounted to a plate. The plate is attached to a guiderail to fix the tension members relative to the hoistway. An edge flange is attached to the plate opposite the guiderails and a strain gauge is attached to the flange. The load exerted by the car suspended by the tension members is transmitted by the plate to the edge flange which is designed such that the force applied to the edge plate by the hoisting ropes causes a large deformation in the edge flange. The strain in the edge flange is measured by the strain gauge.
Japanese patent application 6-255933 describes a load measuring device located at the dead end hitch. The rope terminations pass through a lower plate fixed to a hoistway beam. The rope terminations are fixed to an upper plate, which is pivotally fixed to the lower plate. A load cell is positioned between the upper and lower plates. The load of the car is transmitted through the tension members, to the rope terminations, to the upper plate, forcing it to rotate toward the lower plate thus exerting a force on the load cell proportional to the weight of the car.
The prior art load measurement systems require not only mounting structure but also provisions for transferring the load from the mounting structure to the load measuring device.
The prior art also provides a measurement of the total load as opposed to the load on each tension member
Therefore there exists a need for an improved simplified load measuring apparatus that eliminates the need for complex mounting provisions and provides load measurements for individual tension members.